← Events: on tap, do this lesson New set →

App Dev Worksheet: Events

App development lesson 17: Events: on tap, do this · Set 202 · 40 questions
TalentJR

Developer's tip (When this, do that): Event → handler → action: “on tap, do this”. The handler runs once for every tap. Counter: start + taps × step. A limit stops it growing; on = !on flips ON / OFF.

NameDateTime takenScore ___ / 40
  1. 1.True or false: the user taps Play is a load event. (a) False (b) True
  2. 2.👆 The user types Aman in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Well done, " + nameBox.text + "!";
    };     (a) Well done, Aman! (b) Well done! (c) Aman (d) Well done, nameBox.text!
  3. 3.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome, nameBox.text! (b) Welcome, Kabir! (c) Kabir (d) Welcome!
  4. 4.👆 A tap handler runs how many times if the user taps 4 times? (a) 0 (b) 8 (c) 1 (d) 4
  5. 5.👆 An event in an app is ___. (a) a kind of list (b) an app store (c) a colour theme (d) something that happens
  6. 6.👆 What kind of event is this: the screen first opens? (a) a text event (b) a load event (c) a tap event (d) a timer event
  7. 7.👆 The user taps the button 6 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) ON (b) OFF
  8. 8.👆 The user taps the button 2 times. What number does the label show now?
    let lives = 8;
    button.onTap = function () {
      lives = lives + 3;
      label.text = lives;
    };
  9. 9.👆 What kind of event is this: the user presses Save? (a) a tap event (b) a text event (c) a timer event (d) a load event
  10. 10.👆 What kind of event is this: the user taps Play? (a) a load event (b) a text event (c) a tap event (d) a timer event
  11. 11.👆 Code that runs when an event happens is called a ___. (a) hashtag (b) headline (c) handler (d) header
  12. 12.👆 The user taps the button 7 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) OFF (b) ON
  13. 13.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 5;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  14. 14.👆 The user taps the button 3 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  15. 15.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 5) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  16. 16.👆 The user types Kabir in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Hello, " + nameBox.text + "!";
    };     (a) Hello! (b) Hello, Kabir! (c) Kabir (d) Hello, nameBox.text!
  17. 17.True or false: the user types a letter is a text event. (a) False (b) True
  18. 18.👆 The user taps the button 2 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  19. 19.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 2) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  20. 20.👆 What kind of event is this: one second passes? (a) a timer event (b) a text event (c) a tap event (d) a load event
  21. 21.👆 The user taps the button 7 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 3) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  22. 22.👆 The user taps the button 1 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };
  23. 23.👆 The user taps the button 2 times. What number does the label show now?
    let stars = 2;
    button.onTap = function () {
      stars = stars + 5;
      label.text = stars;
    };
  24. 24.👆 The user taps the button 3 times. What number does the label show now?
    let lives = 5;
    button.onTap = function () {
      lives = lives + 5;
      label.text = lives;
    };
  25. 25.👆 The user taps the button 2 times. What number does the label show now?
    let points = 0;
    button.onTap = function () {
      points = points + 1;
      label.text = points;
    };
  26. 26.👆 Which of these is an event? (a) the font size (b) a list of names (c) the user taps a button (d) the icon colour
  27. 27.True or false: the app starts up is a load event. (a) True (b) False
  28. 28.👆 The user taps the button 3 times. What number does the label show now?
    let points = 5;
    button.onTap = function () {
      points = points + 5;
      label.text = points;
    };
  29. 29.👆 What kind of event is this: a 5-minute alarm ends? (a) a tap event (b) a text event (c) a load event (d) a timer event
  30. 30.👆 The user taps the button 3 times. What number does the label show now?
    let stars = 1;
    button.onTap = function () {
      stars = stars + 3;
      label.text = stars;
    };
  31. 31.👆 The user taps the button 2 times. What number does the label show now?
    let score = 0;
    button.onTap = function () {
      score = score + 3;
      label.text = score;
    };
  32. 32.👆 “On tap → do this” links an event to ___. (a) a charger (b) a font (c) an action (d) a web address
  33. 33.True or false: the screen first opens is a timer event. (a) True (b) False
  34. 34.👆 The user taps the button 6 times. What number does the label show now?
    let stars = 3;
    button.onTap = function () {
      stars = stars + 4;
      label.text = stars;
    };
  35. 35.👆 The user types Zoya in nameBox and taps the button 1 time. What does the label show?
    button.onTap = function () {
      label.text = "Welcome, " + nameBox.text + "!";
    };     (a) Welcome, Zoya! (b) Welcome, nameBox.text! (c) Welcome! (d) Zoya
  36. 36.👆 The user taps the button 4 times. What number does the label show now?
    let score = 3;
    button.onTap = function () {
      score = score + 1;
      label.text = score;
    };
  37. 37.👆 The user taps the button 5 times. What does the label show now?
    let on = false;
    button.onTap = function () {
      on = !on;
      if (on) {
        label.text = "ON";
      } else {
        label.text = "OFF";
      }
    };     (a) ON (b) OFF
  38. 38.👆 What kind of event is this: a countdown hits zero? (a) a load event (b) a timer event (c) a text event (d) a tap event
  39. 39.True or false: one second passes is a text event. (a) True (b) False
  40. 40.👆 The user taps the button 4 times. What number does the label show now?
    let likes = 0;
    button.onTap = function () {
      if (likes < 4) {
        likes = likes + 1;
      }
      label.text = likes;
    };

Answer key

  1. False
  2. Well done, Aman!
  3. Welcome, Kabir!
  4. 4
  5. something that happens
  6. a load event
  7. OFF
  8. 14
  9. a tap event
  10. a tap event
  11. handler
  12. ON
  13. 15
  14. 2
  15. 2
  16. Hello, Kabir!
  17. True
  18. 2
  19. 2
  20. a timer event
  21. 3
  22. 1
  23. 12
  24. 20
  25. 2
  26. the user taps a button
  27. True
  28. 20
  29. a timer event
  30. 10
  31. 6
  32. an action
  33. False
  34. 27
  35. Welcome, Zoya!
  36. 7
  37. ON
  38. a timer event
  39. False
  40. 4

Free app development lessons, practice and worksheets at talentjr.in/app-development-for-students